The trend to go all wireless in high density housing was seemingly a slam dunk just a few years ago. The driving forces behind the exclusive deployment of wireless over wired access was two fold.

Wireless cost savings. It is much less expensive to strafe a building with a mesh network rather than to pay a contractor to insert RJ45 cable throughout the building.

People expect wireless. Nobody plugs a computer into the wall anymore – or do they?

Something happened on the way to wireless Shangri-La. The physical limitations of wireless, combined with the appetite for ever increasing video, have caused some high density housing operators to rethink their positions.

In a recent discussion with several IT administrators representing large residential housing units, the topic turned to whether or not the wave of the future would continue to include wired Internet connections. I was surprised to learn that the consensus was that wired connections were not going away anytime soon.

To quote one attendee…

“Our parent company tried cutting costs by going all wireless in one of our new builds. The wireless access in buildings just can’t come close to achieving the speeds we can get in the wired buildings. When push comes to shove, our tenants still need to plug into the RJ45 connector in the wall socket. We have plenty of bandwidth at the core , but the wireless just does can’t compete with the expectations we have attained with our wired connections.”

I found this statement on a Resnet Mailing list from Brown University.

“Greetings,

I just wanted to weigh-in on this idea. I know that a lot of folks seem to be of the impression that ‘wireless is all we need’, but I regularly have to connect physically to get reasonable latency and throughput. From a bandwidth perspective, switching to wireless-only is basically the same as replacing switches with half-duplex hubs.

Sure, wireless is convenient, and it’s great for casual email/browsing/remote access users (including, unfortunately, the managers who tend to make these decisions). Those of us who need to move chunks of data around or who rely on low-latency responsiveness find themselves marginalized in wireless-only settings. For instance: RDP, SSH, and X11 over even moderately busy wireless connections are often barely usable, and waiting an hour for a 600MB Debian ISO seems very… 1997.”

Despite the tremendous economic pressure to build ever faster wireless networks, the physics of transmitting signals through the air will ultimately limit the speed of wireless connections far below of what can be attained by wired connections. I always knew this, but was not sure how long it would take reality to catch up with hype.

Why is wireless inferior to wired connections when it comes to throughput?

In the real world of wireless, the factors that limit speed include

The maximum amount of data that can be transmitted on a wireless channel is less than wired. A rule of thumb for transmitting digital data over the airwaves is that you can only send bits of data at 1/2 the frequency. For example, 800 megahertz ( a common wireless carrier frequency) has 800 million cycles per second and 1/2 of that is 400 million cycles per second. This translates to a theoretical maximum data rate of 400 megabits. Realistically though, with imperfect signals (noise) and other environmental factors, 1/10 of the original frequency is more likely the upper limit. This gives us a maximum carrying capacity per channel of 80 megabits on our 800 megahertz channel. For contrast, the upper limit of a single fiber cable is around 10 gigabits, and higher speeds are attained by laying cables in parallel, bonding multiple wires together in one cable, and on major back bones, providers can transmit multiple frequencies of light down the same fiber achieving speeds of 100 gigabits on a single fiber! In fairness, wireless signals can also use multiple frequencies for multiple carrier signals, but the difference is you cannot have them in close proximity to each other.

The number of users sharing the channel is another limiting factor. Unlike a single wired connection, wireless users in densely populated areas must share a frequency, you cannot pick out a user in the crowd and dedicate the channel for a single person. This means, unlike the dedicated wire going straight from your Internet provider to your home or office, you must wait your turn to talk on the frequency when there are other users in your vicinity. So if we take our 80 megabits of effective channel bandwidth on our 800 megahertz frequency, and add in 20 users, we are no down to 4 megabits per user.

The efficiency of the channel. When multiple people are sharing a channel, the efficiency of how they use the channel drops. Think of traffic at a 4-way stop. There is quite a bit of wasted time while drivers try to figure out whose turn it is to go, not to mention they take a while to clear the intersection. Same goes for wireless users sharing techniques there is always overhead in context switching between users. Thus we can take our 20 user scenario down to an effective data rate of 2 megabits

Noise. There is noise and then there is NOISE. Although we accounted for average noise in our original assumptions, in reality there will always be segments of the network that experience higher noise levels than average. When NOISE spikes there is further degradation of the network, and sometimes a user cannot communicate at all with an AP. NOISE is a maddening and unquantifiable variable. Our assumptions above were based on the degradation from “average noise levels”, it is not unheard of for an AP to drop its effective transmit rate by 4 or 5 times to account for noise, and thus an effective data rate for all users on that segment from our original example drops down to 500kbs, just barely enough bandwidth to watch a bad video.

Note: This article is written from the perspective of a single wireless router, however all the optimizations explained below also apply to more complex wireless mesh networks.

It occurred to me today, that in all the years I have been posting about common ways to speed up your Internet, I have never really written a plain and simple consumer explanation dedicated to how a bandwidth controller can speed a congested wireless network. After all, it seems intuitive, that a bandwidth controller is something an ISP would use to slow down and regulate a users speed, not make it faster; but there can be a beneficial side to a smart bandwidth controller that will make a user’s experience on a network appear much faster.

What causes slowness on a wireless shared link?

Everything you do on your Internet creates a connection from inside your network to the Internet, and all these connections compete for the limited amount of bandwidth on your wireless router.

Quite a bit of slow wireless service problems are due to contention on overloaded access points. Even if you are the only user on the network, a simple update to your virus software running in the background can dominate your wireless link. A large download often will cause everything else you try (email, browsing) to come to a crawl.

Your wireless router provides first-come, first-serve service to all the wireless devices trying to access the Internet. To make matters worse, the heavier users (the ones with the larger persistent downloads) tend to get more than their fair share of wireless time slots. Large downloads are like the school yard bully – they tend to butt in line, and not play fair.

Also, what many people may not realize, is that even with a high rate of service to the Internet, your access point, or wireless back haul to the Internet, may create a bottle neck at a much lower throughput level than what your optimal throughput is rate for.

So how can a bandwidth controller make my wireless network faster?

A smart bandwidth controller will analyze all your wireless connections on the fly. It will then selectively take away some bandwidth from the bullies. Once the bullies are removed, other applications will get much needed wireless time slots out to the Internet, thus speeding them up.

What application benefits most when a bandwidth controller is deployed on a wireless network?

The most noticeable beneficiary will be your VoIP service. VoIP calls typically don’t use that much bandwidth, but they are incredibly sensitive to a congested link. Even small quarter-second gaps in a VoIP call can make a conversation unintelligible.

Can a bandwidth controller make my YouTube videos play without interruption?

In some cases yes, but generally no. A YouTube video will require anywhere from 500kbs to 1000kbs of your link, and is often the bully on the link; however in some instances there are bigger bullies crushing YouTube performance, and a bandwidth controller can help in those instances.

Can a home user or small business with a slow wireless connection take advantage of a bandwidth controller?

Yes, but the choice is a time-cost-benefit decision. For about $1,600 there are some products out there that come with support that can solve this issue for you, but that price is hard to justify for the home user – even a business user sometimes.

Note: I am trying to keep this article objective and hence am not recommending anything in particular.

On a home-user network it might be easier just to police it yourself, shutting off background applications, and unplugging the kids’ computers when you really need to get something done. A bandwidth controller must sit between your modem/router and all the users on your network.

See for yourself.

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